1. Field
Exemplary embodiments of the present invention relate to a semiconductor design technology and, more particularly, to a data recovery method of a nonvolatile memory device.
2. Description of the Related Art
Semiconductor memory devices included in a data storage system are generally divided into volatile memory devices and nonvolatile memory devices.
A volatile memory device may perform write and read operations at high speed, but data stored therein are lost when its power supply is blocked. On the other hand, in a nonvolatile memory device, the stored data may be retained even without power. However, write and read speeds are relatively slow. Therefore, to retain data regardless of whether there is a constant power supply, a nonvolatile memory device is used. Nonvolatile memory devices include read only memory (ROM), mask ROM (MROM), programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, phase change random access memory (PRAM) magnetic RAM (MRAM), resistive RAM (RRAM), and ferroelectric RAM (FRAM). The flash memory may be NOR type or NAND type.
The flash memory has advantages of RAM in that program and erase operations may be freely performed, and advantages of ROM in that the stored data may be retained even without a constant source of power. Flash memories are widely used as storage media of portable electronic appliances such as digital cameras, personal digital assistants (PDA) and MP3 players.
Reliability of data in memory storage systems is regarded as an important issue.